Tow truck switching means



United States Patent Inventor Karl R. M. Karlstrom o Roseville, MichiganAppl. No. 730,881

Filed May 21, 1968 Patented Nov. 24, 1970 Assignee American Chain andCable Company, Inc.

New York, New York a corporation of New York TOW TRUCK SWITCHING MEANS22 Claims, 7 Drawing Figs.

US. Cl 104/88, 104/ 172 Int. Cl. B61] 3/04 Field 01' Search 104/88, 96,172

References Cited UNITED STATES PATENTS 3,081,710 3/1963 Dehne 104/883,316,856 5/1967 Edgar 104/88 3,406,638 10/1968 Braun 104/88 3,418,94512/1968 Stevenson et al 104/172 Primary Examiner-Arthur L. La PointAssistant Examiner-Robert Saifer Attorney-Barnes, Kisselle, Raisch &Choate ABSTRACT: A tow truck conveyor system comprising a track definedby slots in the floor including a main track portion and a branch trackportion. A plurality of tow trucks with tow pins extending downwardly inthe slots are movable along the main track portion by a chain operatingbeneath the floor. A switch tongue is provided at the area of junctureof the main track portion and the branch track portion. The switchtongue is operated when signal reader elements in the floor are engagedby signal members on the tow truck.

'Pa tented Nov. 24, 1970 Sheet INVENTOR. KARL R. M. KARLSTROM ATTORNEYS'Paten ted Nov. 24, 1970 Sheet 2 of3 IN.VENTOR. KARL R. M. KARLSTROMATTORNEYS Patented Nov. 24, 1970 3,541,963

Y// 4O 3 L 20 l6 I ////,I l k:\ I mum I i 26 I i ,9 27 I 5 I 2/ FIG. 7

INVENTOR. KARL. R. M. KARLSTROM ATTORNEYS TOW TRUCK SWITCHING MEANS Thisinvention relates to conveyor systems and particularly to tow truckconveyor systems.

It is common'to provide a conveyor system with tow trucks that have towpins that extend downwardly into slots, which define the track in thefloor, into engagement with a chain beneath the floor to pull the towtrucks along the floor. In the handling of such tow trucks, it is alsocommon to have branch track portions and switch tongues for divertingthe tow trucks to the branch track portion.

Among the objects of this invention is to provide a simple low costsystem for actuating the switch tongue in response to signals from thetow truck, which system utilizes a minimum number of parts, is easy tomaintain, occupies a small space vertically in the floor, and has longlife.

In the drawings:

FIG. l is a fragmentary plan view ofa system embodying the invention.

FIG. 2 is a fragmentary view similar to FIG. I of a modified systemshowing the parts in a different position.

FIG. 3 is a fragmentary vertical view through a portion of the system.

FIG. 4 is a view similar to FIG. I on an enlarged scale with partsbroken away.

FIG. 5 is a fragmentary sectional view on an enlarged scale taken alongthe line 5-5 in FIG. 4.

FIG. 6 is a fragmentary sectional view on an enlarged scale taken alongthe line 6-6 in FIG. 4.

FIG. 7 is a fragmentary sectional view taken along the line 7-7 in FIG.4.

Referring to FIGS. 1 and 3, the system embodying the invention comprisesa-floor 10 having a slot 11 therein which defines a main track and aslot 12 intersecting the slot 11 and defining a branch track. Aplurality of carriers in the form of tow trucks 13 having wheels 14 areprovided. Each tow truck 13 includes a tow pin 15 extending downwardlythrough the slot 11 into engagement with a trolley or pusher 16 that isfixed to a chain 17 driven in a manner not shown.

At the area of juncture of the main track 11 and branch track 12 aswitch tongue 18 is provided. As shown in FIGS. 4 and 7, the switchtongue 18 is provided with a tube 19 which is telescoped over a fixedshaft 20 that extends between a floor plate 10a and a frame or housing21. A latch lever 22 is also fixed to the tube 19/ Latch lever 22 isyieldingly urged in a direction tending to move the switch tongue intoposition where itwill divert a tow pin 15 by a spring 23 that is fixedat one end to the latch lever 22 and at the other end to a support 24fastened to the housing 21. The switch tongue 18 is normally held out ofthe position wherein it would divert the tow pin ofa tow truck by aplurality of latches 25 which are pivoted on a shaft 26 that is fixed tothe housing 21 and extends vertically. Each latch 25 includes a notch 26that engages a roller 27 on the latch lever 22. The rollers 27 arerotatably mounted on a pin 28 that extends vertically upwardly from thelatch lever 22 (FIG. 7). Each latch 25 is urged against the roller 27 ofits respective latch lever 22 by a spring 251; which is connected at oneendto the latch 25 and at the other end to the housing 21.

Referring to FIGS. 1, 4 and 5, each latch 25 has a signal reader element29 associated therewith. Each signal reader element is pivoted to abracket 30 fixed to housing 21 and is adapted to swing upwardly andrearwardly to the broken line position shown in FIG. 5 through anopening 32 in the fioor plate 10a into the path of a signal member 33 onthe tow truck. Each signal reader element 29 is urged toward a positiondownwardly and forwardly within the floor by a tension spring 34 that isfixed at one end to the signal reader element 29 and at the other end toa bracket 35 on housing 21. A cable C is fixed at one end to each latch25 by a lever 36 and at the other end to its respective signal readerelement 29 as at 37. Each cable C is trained over a pair of pulleys 38,39 mounted on brackets 40, 41 fixed t0 the frame 21 for rotation aboutvertical axes. Each cable C is further trained over a pulley 42rotatably mounted on a bracket 43. A spring 36a has one end thereofconnected to lever 36 and the other end thereof connected to housing 21to take up any slack in cable C.

As shown in FIGS. 4 and 6 all ofthe pulleys 38 are mounted on the singlebracket 40. In the same manner, all of the pulleys 39 are mounted on thesingle bracket 41. As shown in FIGS. 1 and 4, two signal reader elementsare provided in side by side relation in one of a plurality of positionsP shown in broken lines in FIG. I.

In order to elevate the signal reader elements 29 into the path of thetow truck when it approaches the area of juncture of the main track andbranch track, a conditioning lever 44 is pivoted about a vertical axison a pin 45a and extends in the direction of travel of the tow trucksfor swinging movement into and out of the path of the tow pin as itmoves in the slot 11. An idler pulley 45 for each cable C is mounted ona bracket 46 on lever 44. The reach R of each cable C between itspulleys 38, 39 extends adjacent its respective pulley 45.

Lever 44 is normally in the path of the tow pins 15. As a tow truckapproaches and its tow pin 15 engages the lever 44. the lever is swunglaterally or downwardly as viewed in FIG. 4, bringing the pulley 45 intocontact with the cables and applying tension to the cables to elevatethe signal reader elements 29 to the broken line position shown in FIG.5. As the tow truck is moved further along the slot, if the signalreader elements 33 are properly positioned and correspond in position tothe position of the signal elements 33 on the tow truck, the signalreader elements 29 will be engaged and swung downwardly and forwardly.This movement of signal reader elements 29 applies tension to the cablesC to pull the latch elements 25 out of engagement with the rollers 27 onlatch lever 22 releasing the latch lever 22 to permit the spring 23 toswing the switch tongue 18 into the path of the tow pin and therebydivert the tow truck (FIG. 1). If the signal elements 33 on the towtruck are not positioned properly, for example, if only one of aplurality of signal reader elements are engaged or none is engaged, atleast one of the latches 25 will remain in engagement with the latchlever '22 so that the switch tongue will not be actuated.

In order to prevent diverting the tow truck into a branch slot 12 whichalready has a carrier therealong, a choke system is provided whichincludes choke latch 50 pivoted on the shaft 26 and having a notchtherein engaging one of the rollers 27 on latch lever 22. The chokelatch 50 is normally held out of engagement with its respective rollerby a spring 51 operating through a lever 52. However, if a tow truck ispresent in the branch'slot 12, its tow pin will engage a lever 52 in theslot 12 applying tension to a cable 53 trained over a pulley 54 to urgethe choke lever 50 into engagement with the latch lever 22 therebypreventing the latch lever 22 from moving and, in turn, the switchtongue from moving to the diverting position.

In the form of the invention shown in FIG. 2, two additional 7 signalreader elements 29 and associated latches 25, pulleys ments 33 on thetow truck.

Although the system has been described in connection with asubfloorconveyor system, it is also applicable to overhead power and freeconveyor systems comprising main and branch tracks with an associatedswitch tongue.

Iclaim: 1. The combination comprising: a track including a main trackportion and a branch track portion; a carrier movable along said track;switch means at the area of juncture of the main track portion andbranch track portion for diverting the carrier from the main trackportion to the branch track portion;

latch means forfholding said switch means in one of its two positions;

means yieldingly urging said switch means to its other position; 1

a flexible element connected to said latch means;

at least one signal reader element movable into and out of the path ofthe carrier;

means in the path of the carrier and operable by the approach of acarrier to apply tension to said flexible element to move said signalreader element into the path of the the carrier; and

signal means on the carrier operable when properly positioned to engagesaid signal reader element and apply further tension to said flexibleelement to disengage said latch means and permit said switch means tomove to its other position under the action of said yielding means.

2. The combination set forth in claim 1 wherein said signal readerelement is movable in such a manner that it swings out and rearwardlyinto the path of the carrier and in and forwardly out of the path of thecarrier.

3. The combination set forth in claim 1 including a plurality of saidsignal reader elements and a flexible element and latch means individualto each said reader element.

4. The combination set forth in claim 1 wherein said means in the pathof said carrier and operable to apply tension to said flexible elementcomprises a member pivoted adjacent the path and normally in the path ofthe carrier.

5. The combination set forth in claim 4 wherein said flexible elementhas a reach thereof extending across a pair of pulleys, saidlast-mentioned means having a pulley engaging said reach to apply saidtension to said flexible element upon movement of said last-mentionedmeans.

6. The combination set forth in claim 1 including a choke elementoperable upon said latch means, said choke element being engaged by acarrier along said branch track portion to prevent disengagement of saidlatch means.

7. The combination set forth in claim 1 including means yieldinglyurging said signal reader element in a direction out of the path of saidcarrier.

8. The combination set forth in claim 1 including means yieldinglyurging said latch means into engagement with said switch means;

9. The combination set forth in claim 1 wherein said switch meanscomprises a switch tongue pivotally mounted adjacent the area ofjuncture of-said main track portion and branch track portion, saidlatch, means including latch elements pivoted adjacent said s'witchtongue and engaging said switch tongue.

10. The combination comprising:

a floor having slots therein defining a main track portion and a branchtrack portion;

a conveyor driven beneath said floor along said main track portion; v

a tow truck movable along said floor;

said tow truck having a tow pin extending downwardly through said slotin said floor into engagement with said conveyor;

switch means at the area of juncture of the main track portion andbranch track portion for diverting the tow pin of the tow truck from themain track portion to the branch track portion;

latch means for holding said switch means in one of its two positions;

means yieldingly urging said switch means to its other posi tron;

a flexible element connected to said latch means;

at least one signal reader element movable upwardly into and out of thepath of the tow truck;

said flexible element being attached to said signal reader element;

means in the path of the tow truck and operable to apply tension to saidflexible element to move said signal reader element into the path of thetow truck; and

signal means on the tow truck operable when properly positioned toengage said signal reader element and apply further tension to saidflexible element to disengage said latch means and permit said switchmeans to move to its other position under the action of said yieldingmeans.

11. The combination 34 set forth in claim 10 wherein said signal, readerelement is movable in such a manner that it swin s upwardly andrearwardly into the path of the tow truck and ownward y and forward yout of the path of the tow truck.

12. The combination set forth in claim 10 including a plurality of saidsignal reader elements and a flexible element and latch individual toeach said reader element.

13. The combination set forth in claim 10 wherein said means in the pathof said tow truck and operable to apply tension to said flexible elementcomprises a member pivoted adjacent main track portion and normally inthe path of the tow pin of the tow truck.

14. The combination set forth in claim 13 wherein said flexible elementhas a reach thereof extending across a pair of pulleys, saidlast-mentioned means having a pulley engaging said reach to apply saidtension to said flexible element upon movement of said last-mentionedmeans.

15. The combination set forth in claim 10 including a choke elementoperable upon said latch means, said choke element being engaged by thetow pin of a tow truck along said branch track-portion to preventdisengagement of said latch means.

16. The combination set forth in claim 10 including means yieldinglyurging said signal reader element in a direction out of the path of saidtow truck.

17. The combination set forth in claim 10 including means yieldinglyurging said latch means into engagement with said switch means.

18. The combination set forth in claim 10 wherein said switch meanscomprises a switch tongue pivotally mounted adjacent the area ofjuncture of said main track portion and branch track portion, said latchmeans including latch elements pivoted adjacent said switch tongue andengaging said switch tongue.

19. The combination set forth in claim 10 including a plurality of saidsignal reader elements in laterally disposed relation adjacent the pathof the carrier, a flexible element and latch means individual to eachsaid signal reader element.

20. The combination set forth in claim 19 wherein at least one of saidsignal reader elements is on an opposite side of said main trackportion.

21. The combination set forth in claim 1 including a plurality of saidsignal readerelements in laterally disposed relation adjacent the pathof the carrier, a flexible element and latch means individual to eachsaid signal reader element.

22. The combination set forth in claim 21 wherein at least one of saidsignal reader elements is on an opposite side of said main trackportion.

